Groundwater Contractors in Pinal County, AZ

Groundwater Contractors in Pinal County, Arizona

Pinal County straddles the transition between the Phoenix and Tucson metros — it is one of the fastest-growing counties in the United States, driven by housing development in Queen Creek (shared with Maricopa County), San Tan Valley, Maricopa city, and Coolidge. This rapid growth has placed enormous pressure on the county’s groundwater resources, which are managed under the Pinal Active Management Area (Pinal AMA).

Groundwater in the Pinal AMA

The Pinal AMA has a unique regulatory situation: unlike the Phoenix or Tucson AMAs, the Pinal AMA’s long-term goal is not necessarily safe yield. The AMA was established with the recognition that it would undergo a transition from heavy agricultural use to urban development, and that some degree of groundwater mining would occur during that transition.

That transition is happening faster than anyone anticipated. As agricultural operations reduce pumping or are converted to residential development, the AMA’s groundwater budget is being reorganized. New large-scale housing developments are required to demonstrate a 100-year adequate water supply — a requirement that has led to complex water supply deals involving CAP water, reclaimed water, and groundwater credits.

Key Aquifer Areas

Apache Junction (East Valley): Sitting at the base of the Superstition Mountains, Apache Junction is at the eastern edge of the Salt River Valley basin. Well depths here run 300–700 feet through alluvial sediments. The Goldfield Mountains and Superstition block recharge from the east, making local groundwater management important.

Marana (Northwest Tucson Fringe): Technically in the northwest, Marana extends into both Pima and Pinal counties. The Avra Valley and Marana sub-basin have been heavily used for cotton and alfalfa irrigation historically. Well depths are typically 150–400 feet.

Water Quality in Pinal County

Arsenic: Pinal County has some of the highest naturally occurring arsenic concentrations in Arizona. Parts of the county exceed 50 µg/L — five times the EPA MCL. Water testing and treatment are essential for any new well.
Nitrates: Agricultural history throughout the county has left elevated nitrate signatures in some shallow wells.
Hardness: Very hard, 350–600 mg/L; water softeners are standard for well users.
PFAS: Luke AFB’s PFAS plume extends into portions of western Maricopa and possibly into Pinal County. Monitor ADEQ advisories.